Conventional spark plug assemblies suffer from a number of disadvantages, resulting in inefficient, ineffective and/or uneven cumbustion at or in the vicinity of the associated cylinder of the internal combustion engine, one result of which can be the build-up of undesirable carbon and/or other impurities on the electrodes of the spark plug assembly ultimately affecting the overall operation of the spark plug assembly. Known spark plug assemblies also have a tendency to produce undesirable "pre-ignition". Furthermore, known spark plug assemblies are also somewhat unreliable in "firing" unless the conditions prevailing in their immediate vicinity are correct, for example, the presence of substances such as oil have been found to prevent "firing".
Conventional spark plugs have also been found to suffer from heat transfer problems, particularly when associated with high-performance engines where it has been found that heat transfer through the spark plug assembly often results in undesirable over heating, and ultimately, damage to the insulator body of the plug.
As one example of known spark plug assemblies, attention is directed to Australian Patent Specification No. 159,863 which discloses a spark plug fitted with an adaptor defining a pre-combustion chamber. The spark plug employed therein was of a conventional design capable of working normally without the adaptor, although without the adaptor the plug suffered in performance as a result of the loss of the anti-fouling capability achieved with the adaptor. However, such a combination of spark plug and adaptor has now been found to result in a long heat transfer path, and with the advent of more sophisticated high-performance engines, arrangements such as those disclosed in the patent Specification No. 159,863 have been found to suffer as a result of the undesirable over-heating referred to above.
The present invention therefore seeks to alleviate the problems and disadvantages associated with known spark plug assemblies, and to provide a spark plug which will allow for even combustion of the combustible gases in the cylinder of an associated internal combustion engine.